QUICK EXPLANATION: I'm looking for a way to check each record in result from MySQL Server 1 (MySQL1) quickly against those already in MySQL Server 2 (MySQL2) and make decisions on whether to keep them or not based on business rules.

DETAILED EXPLANATION:
I am building a PHP script to move data from a MySQL database on one server (MySQL1) to a MySQL Instance on a different server (MySQL2).

I am retrieving records with an end_date column value that falls between the current date and the date of the last collection. One of the columns is a unique identifier, ProjectID, which will be stored in MySQL2

ISSUE:
I need to verify that no project records retrieved from MySQL1 are duplicates of those already inserted into MySQL2 from a previous collection (this case could occur in a few scenarios, for example, a user changes the end date column for a project). Once I have a SELECT result from MySQL1, say:


how do I check these project_ids against those already in MySQL2:


If a project_id is a duplicate but has a different end_date, I want to keep the most recent.

If a project_id is a duplicate and the rest of the record is identical, I want to ignore the new record.

Thanks for the help!